Yohei and Rosalie met at a pub and entered into an international marriage. However, Yohei was left utterly exhausted by Rosalie’s uninhibited nature and insatiable appetite for intimacy. One day, his younger stepsister, Mai, came to visit him; although they had long been separated following their parents' divorce, Mai revealed that she had been left completely alone in the world since then. Seeing Yohei treat his sister with such kindness, Rosalie grew jealous and ran away from home. Undeterred, Yohei decided to let Mai stay with him, but...